The present invention is drawn to ink-jet ink media, systems, and methods for reducing air fade of ink-jet produced images. In one detailed aspect, the present invention is drawn to the preparation of interpolymer complexes for the sealing of ink-jet produced images on porous media.
Computer printing technology has evolved to a point where very high resolution images can be prepared on various types of media. This has been, in part, why inkjet printing has become a popular way of recording images on various media, particularly paper. Other reasons include low noise, capability of high speed recording, and multi-color recording. Additionally, these advantages can be obtained at a relatively low price to consumers. Though there has been great improvement in ink-jet printing, accompanying this improvement are increased demands on ink-jet printing, e.g., higher speed, higher resolution, full color image formation, image permanence, etc.
There are several characteristics to consider when evaluating a printer ink in conjunction with a printing surface or substrate. Such characteristics include edge acuity and optical density of the image on the surface, dry time of the ink on the substrate, adhesion to the substrate, lack of deviation of ink droplets, presence of all dots, resistance of the ink after drying to water and other solvents, long-term storage stability, and long-term reliability without corrosion or nozzle clogging. In addition to these characteristics, when printing on inorganic porous media substrates, light fade and air fade resistance is also an issue for consideration. Though the above list of characteristics provides a worthy goal to achieve, there are difficulties associated with satisfying all of the above characteristics. Often, the inclusion of an ink component meant to satisfy one of the above characteristics can prevent another characteristic from being met. Thus, most commercial inks for use in ink-jet printers represent a compromise in an attempt to achieve at least an adequate response in meeting all of the above listed requirements.
Papers used for ink-jet printing have typically included high-quality or wood-free papers designed to have a high ink absorptivity. These papers are functionally good for ink-jet printing because the ink-jet inks may be absorbed readily and dry quickly. However, such papers often do not allow for a crisp or sharp image.
In order to attain enhanced print quality and image quality as in a photograph, special media has been developed to work with aqueous inks. For example, various coated papers have been prepared for use with ink-jet printing technology. Existing ink-jet media used in digital imaging can be separated into two broad groups: porous media and swellable media.
With porous media, an ink receiving layer can comprise a porous inorganic oxide (usually silica or alumina) bound together by some polymer binder, and optionally, mordants or ionic binding species, e.g., cationic binding species for use with anionic dyes or anionic binding species for use with cationic dyes. During printing, ink is quickly absorbed by the physical porosity of the media, and if an ionic binding species is present, the dye is attracted to the ionic species of opposite charge. In other words, the colorant (typically a dye) can be bound either by mordants incorporated into porous layer, or by the inorganic oxide surface itself. This type of media has the advantage of relatively short dry-times, good smearfastness, and often, acceptable water and humidity resistance. However, porous media often exhibits poor fade resistance (both in light and dark conditions), and sometimes exhibits poor water and humidity resistance.
Conversely, with swellable media, an ink receiving layer is present that comprises a continuous layer of a swellable polymer that is not physically porous. Upon printing, ink is absorbed as water contacts and swells the polymer matrix. The colorant (typically a dye) can be immobilized inside the continuous layer of the polymer with significantly limited exposure to the outside environment. Advantages of this approach include much better fade resistance (in both light and dark conditions) than is present with porous media. However, swellable media requires a longer dry time and exhibits poor smearfastness.
Though both swellable media and porous media each provide unique advantages in the area of ink-jet printing, new media and a system for printing images that provide advantages from both systems while minimizing their respective disadvantages would be an advancement in the art.
It has been recognized that it would be advantageous to develop ink-jet ink media, systems, and methods that provide the advantages of both porous media and swellable media. Specifically, the present invention provides a media sheet, comprising a substrate, a porous dye-receiving layer deposited on the substrate, and a porous ionic layer deposited on the porous dye-receiving layer. The porous dye-receiving layer can comprise a metal or semi-metal oxide bound by a polymeric binder. The porous ionic layer can comprise particulates having ionically-charged surfaces.
The media sheet can include other added materials, including an ink-jet ink deposited on the porous ionic layer, wherein the ink-jet ink comprises an ink vehicle and a dye. The dye can have the same polarity as the ionically-charged surfaces, and the ink vehicle can be substantially free of components that would substantially react with the ionically-charged surfaces. In an alternative embodiment, a fluid sealant composition can be deposited on the porous ionic layer forming an interpolymer complex. Such a fluid sealant composition can comprise a substantially uncrosslinked water soluble or dispersible polymer having an opposite polarity than the ionically-charged surfaces.
In accordance with an alternative detailed aspect of the present invention, a system of generating ink-jet images can comprise a properly configured media sheet, an ink-jet ink, and a fluid sealant composition. The media sheet can comprise a substrate, a porous dye-receiving layer deposited on the substrate, and a porous ionic layer deposited on the porous dye-receiving layer. The porous dye-receiving layer can comprise a metal or semi-metal oxide bound by a polymeric binder, and the porous ionic layer can comprise particulates having ionically-charged surfaces or can comprise ionically-charged water-soluble polymers. The ink-jet ink can comprise an ink vehicle and a dye, wherein the dye has the same polarity as the ionically-charged species in the porous ionic layer, and the ink vehicle is substantially free of components that would substantially react with the ionically-charged surfaces or species in the porous ionic layer. Thus, when the ink-jet ink is printed onto the media sheet, the inkjet ink passes through the porous ionic layer and is deposited on the porous dye-receiving layer forming an ink-jet ink-containing media sheet. A fluid sealant composition can then be deposited that comprises a substantially uncrosslinked water soluble or dispersible polymer having an opposite polarity compared to the ionically-charged surfaces. Upon deposition of the fluid sealant to the ink-jet ink-containing media sheet, an interpolymer complex can be formed, sealing the ink-jet ink in the media sheet.
In another aspect of the present invention, a method of ink-jet recording can comprise the steps of providing an appropriately configured media sheet, ink-jet printing an appropriately configured ink-jet ink onto the media sheet, and sealing the ink-jet ink in the media sheet with an appropriately configured fluid sealant composition. The media sheet can comprise a substrate, a porous dye-receiving layer deposited on the substrate, and a porous ionic layer deposited on the porous dye-receiving layer. The porous dye-receiving layer can comprise a metal or semi-metal oxide bound by a polymeric binder, and the porous ionic layer can comprise particulates having ionically-charged surfaces. The ink-jet ink can comprise an ink vehicle and a dye, wherein the dye has the same polarity as the ionically-charged surfaces, and the ink vehicle is substantially free of components that would substantially react with the ionically-charged surfaces. With this combination or configuration, the media sheet can accept the ink-jet ink without substantial reaction at the porous ionic layer, thereby forming an ink-jet ink-containing media sheet. The sealing step can occur using a fluid sealant composition comprising a substantially uncrosslinked water soluble or dispersible polymer having an opposite polarity as the ionically-charged surfaces. Upon application of the fluid sealant to the ink-jet ink-containing media sheet, an interpolymer complex can be formed that seals the ink-jet ink in the media sheet.
Additional features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the invention.